In a method for manufacturing the nonvolatile semiconductor memory device, for example, a flash memory, there is a step of tentatively forming a memory cell area into a fin shape. With the progress of microfabrication of the memory cell, an aspect ratio of the fin-shaped memory cell area is increased in the step, and unfortunately sometimes the fin-shaped memory cell area collapses.
In order to solve the problem, a hybrid structure was developed in which a charge storage layer of the memory cell is formed by stacking a floating gate layer and a charge trap layer. The hybrid structure attracts attention as a technology of reducing the aspect ratio of the fin-shaped memory cell area during the manufacturing process, because a height of the charge storage layer can be suppressed.
However, in the memory cell having the hybrid structure, it is difficult to simultaneously satisfy improvements of a write characteristic and a data retaining characteristic.